Work has continued on the effort to measure the fusion of single vesicles to planar membranes. Systems have been developed for the formation of large unilamellar vesicles and planar membranes, and we are working towards reliably patch clamping them. A novel electrical configuration has been adopted in which the pipette and surrounding bath are maintained at ground potential, and the solution on the trans side of the bilayer is stimulated with an a.c. voltage. This configuration sidesteps the normal problems associated with large pipette and membrane capacitances and provides for a nearly background free measurement limited only by amplifier noise.